Conversion of hydrocarbon oils



Feb. 5, 1935. M. w. BARNES 1,989,731

r v CONVERSION OF HYDROCARBON OILS Filed May 27, 1952 VAPORIZING, FLASHDISTILLING OR COKNG CHAMBER FURNACE INVENTOR MARION W. BARNES W ZEWATTORN 7' Patented Feb. 5, 1935 I 1,989,731

UNITEDSTATES PATENT OFFICE.

CONVERSION OF HYDROCARBON OILS Marion W. Barnes, Chicago, Ill., assignorto Universal Oil Products Company, Chicago, 111., a corporation ofDelaware Application May 2'7, 1932, Serial No. 613,875

3 Claims. (Cl. 196-49) This invention relates to the conversion ofhysystem are condensed and separated into a heavy dr'ocarbon oils andmore particularly refers to an fraction, containing any coke-formingresidual improved process and apparatus especially adaptmaterial carriedover with the vapors from the ed to the conversion of relatively heavyoils to flash distilling operation, and lower boiling frac- 5 producemaximum yields of light distillate prodtions, subjecting said lowerboiling fractions of 5 ucts, such as motor fuel of high anti-knockvalue, the reflux condensate to conversion temperature and a residualproduct of controlled quality. at superatmospheric pressure in a heatingcoil In cracking processes wherein the raw oil chargand communicatingreaction chamber, returning ing stock is subjected to conversion in thesame said heavy components of the reflux condensate heating coil withlighter insufllciently converted directly to the reaction chamber,subjecting re- 10 intermediate products of the operation milder sidualliquid from the reaction chamber to furconversion temperatures must beutilized when ther vaporization at reduced pressure, subjecting thecharging stock is of relatively heavy nature, vapors from both theconversion and flash disthan the conversion temperature best suited fortilling operations to fractionation, as already del5 the treatment ofthe reflux condensate (interscribed, subjecting raw oil charging stockfor the mediate conversion products), in order to prevent system toindependently controlled conversion the excessive formation anddeposition of coke conditions inaseparate heating coil and introducinthe heating coil. Furthermore, in the type ing the heated material intothe reduced pressure of process now in favor wherein the residualvaporizing chamber together with the residual products formed under highsuperatmospheric liquid conversion products from the reaction 20pressure are subjected to flash distillation at rechamber. ducedpressure for further vaporization and While the process of the presentinvention is wherein reflux condensate from the flashed vaparticularlyadapted to the treatment of relapors is returned to the heating coil ofthe system tively heavy charging stock such as heavy crudes,

together with reflux condensate from the cracked residual oil, fuel oiland the like, it may also be 25 vapors, the combined reflux condensatesoften utilized to advantage for the treatment of lower contain smallamounts of heavy residual material boiling oils and is not limited toany particular which have been carried over with the vapors type ofcharging stock. from the flash distilling chamber, which con- Theattached diagrammatic drawing illustrates taminating material in thereflux is especially one specific form of apparatus incorporating the,30 susceptible to coking under the conditions emfeatures of the presentinvention. These features ployed in the heating coil and often leaves aand the advantages will be more clearly underdeposit of carbon on thewalls of the heating stood by reference to the following description oftubes, which necessitates short operating periods the drawing.

and prolonged clean-out time. Heating coil 1 is located within a furnace2 of 35 By use of the novel features of the present inany suitable formand the oil supplied to this vention the above mentioned troubles areelimzone is heated to the desired conversion temperinated as neither theraw oil charging stock or ature preferably at substantialsuperatmospheric the heavy components of the reflux condensate pressureand is discharged through line 3 and pass through the high temperatureheating coil valve 4 into reaction chamber 5 which is also 40 whereinthe lighter reflux condensate is subjected preferably maintained atsubstantial superatmosto further conversion. This practice permits thepheric pressure. use of more severe conversion conditions, to whichFinal separation of vaporous and residual liquid said light refluxcondensate is best suited, withconversion products may or may not beaccomout encountering coking difliculties and yet also plished inchamber 5, as desired, and the heated 45 permits the desired degree ofconversion for both oil from heating element 1 may be introduced in theraw oil charging stock and the heavy compothis zone at any desired pointalthough the drawnents of the reflux condensate. ing shows only onepoint of introduction. Re-

In one of its speciflc embodiments the invention sidual liquid iswithdrawn from the reaction '50 may comprise subjecting vapors resultingfrom chamber through line 6 and valve 7 to further 5 the conversion ofhydrocarbon oil and subsequent vaporization in vaporizing or flashdistilling flash distillation of the residual liquid conversion chamber8 and vaporous conversion products may products to fractionation wherebythe compoeither be withdrawn together with the residual nents of thevapors boiling above the end boiling liquid to chamber 8, in the mannerdescribed, or

point of the desired final light product of the may be separatelyremoved from the reaction 55 chamber through line 9 and valve 10 andsubjected to fractionation in fractionator 11.

Raw oil charging stock for the system may be supplied through line 12and valve 13 to pump 14 from which it is fed through line 15 and valve16 into heating coil 17, which is located within a furnace 18 of anysuitable form capable of heating the raw oil charging stock to thedesired conversion temperature under the desired pressure. The heatedraw oil from heating coil 17 may be discharged through line '19 andvalve 20 into line 6, commingling therein with the material from chamber5, withdrawn through this line, and passing therewith to chamber 8, orthe heated raw oil may be separately introduced into chamher 8 at anydesired point by well known means, not, illustrated in the drawing.

vaporizing or flash distilling chamber 8 preferably employs asubstantially reduced pressure relative to that utilized in reactionchamber 5 and the residual liquid conversion products from chamber 5 aresubjected to further vaporization in this zone together with the heatedraw oil from heating coil 1'7. The process may be operated for theproduction of either residual liquid or a substantially non-fluidresidual material such as petroleum coke or asphalt. Residual liquid orasphaltic material, when such is produced, may be withdrawn from chamber8 through line 21 and valve 22 to cooling and storage or to any desiredfurther treatment. When the residual product of the process is reducedto coke in chamber 8 it may be allowed to accumulate in this zone to beremoved therefrom when the operation of the chamber is discontinued and,when desired, a plurality of coking zones, similar to chamber 8 but notillustrated in the drawing, may be employed and may be operated eitheralternately or simultaneously to provide additional space for theaccumulation of coke and thus prolong the operating cycle of theprocess. Vaporous products are wi ridrawn from chamber 8 through line 23and valve 24 to line 9 and may pass thence to fractionation infractionator 11 together with the vaporous products, if any, withdrawnfrom chamber 5 through line 9 and valve 10, as already described.

The vapors supplied to fractionator 11, comprising vaporous productsresulting from both the conversion and flash distillation or cokingoperations, are separated by fractional condensation into three majorfractions. The heaviest components of the vapors, including any residualmaterial of cokeforming characteristics carried over with the vaporsfrom chamber 8, collect, as heavy reflux condensate in the lower portionof the fractionator, are withdrawn therefrom through line 25 and valve26 to pump 27 by means of which they are returned through line 23 andvalve 29'to reaction chamber 5, entering this zone at any desired point,and being subjected therein to further conversion by direct contact withthe heated materials from chamber 5. The intermediate components of thevapors, which boil above the boiling point of the desired. final lightproduct of the system, are also condensed within the fractionator andmay be withdrawn as a side stream or streams of light reflux condensatethrough one or a piurality of lines 30 controlled by valves 31 and passthrough line 32 to pump 33, by means of which they are fed through line34 and valve 35 to heating coil 1 and comprise the only materialsupplied to this heating coil. The lightest components of the vaporssupplied to iraotionator 11, comprising materials within the boilingrange of the desired final light product of the system and gas, areremoved from the upper portion of the fractionator through line 36 andvalve 37, are subjected to condensation and cooling in condenser 38 fromwhich the resulting distillate and uneondensable gas passes through line39 and valve 40 to be collected in receiver 41. Uncondensable gasmay bereleased from the receiver through line 42 and valve 43. Distillate maybe withdrawn from the receiver through line 44 and valve 45.

Any of the usual operating expedients such as recirculating a portion ofthe distillate from the receiverof the system to the upper portion ofthe fractionator to assist cooling and fractionation in this zone andpreheating a portion or all of the raw oil charging stock by heatrecovered from within the system may be employed without departing fromthe scope of the invention although such well known features are notillustrated in the accompanying drawing.

Conversion temperatures employed within the heating coil to which thelight reflux condensate is supplied may range from 900 to 1050 F. orthereabouts, preferably with superatmospheric pressure of from to 500pounds, or more per square inch. Substantially this same range ofpressures may be employed in the reaction chamber but the vaporizing orcoking chamber as well as. thesucceeding fractionating, condensing andcollecting portions of the system are preferably maintained at asubstantially reduced pressure ranging from 100 pounds, or thereabouts,per square inch down to substantially atmospheric pressure. The heatingcoil to which the raw oil charging stock is supplied may utilizeconversion conditions either more or less severe than those to which thelight reflux condensate is subjected, depending upon the nature of thecharging stock. With heavy charging stocks, such as crudes, residualoil, fuel oil and the lure, a milder conversion temperature than that towhich the light reflux is subjected, ranging, for example, from 800 to950 F., may be employed in the raw oil heating coil with pressuresranging from 100 to 500 pounds, or thereabouts, per square inch. Whenrelatively light charging stock such as gas oil, l-zerosene distillate,pressure distillate bottoms, naphtha, straight-run gasoline, etc., areemployed, higher conversion temperatures ranging, for example, from 900to 1100 R, my be employed the raw oil heating coil with pressures whichmay range from substantially atmospheric to 800 pounds, or more, persquare inch.

As a specific example of the operation of the process of the presentinvention, the raw oil charging stock is an 18 A. P. I. gravitymid-continent fuel oil which is subjected to a temperature of about 890F., at a pressure of approximately 200 pounds per square inch, and isthen introduced into the flash distilling chamber. Light refluxcondensate from the fractionator of the system, having an end boilingpoint of approximately 650 F., is independently subjected to aconversion temperature of approximately 925 F., at a superatmosphericpressure of about 350 pounds per square inch and is then introduced intothe reaction chamber which is maintained at about the same pressure. Thevaporizing chamber is maintained at a pressure of approximately 50pounds per square inch, which pressure is substantially equalized in thesucceeding fraction-sting, condensing and collecting equipment. Heavyreflux condensate having an initial boiling point of about 650 F. isreturned directly to the reaction chamber. This operation may yield, perbarrel of raw oil charging stock, about 55% of motor fuel having ananti-mock value equivalent to an octane number of approximately 78,about 38% of residual oil suitable for sale as fuel, the remainder beingchargeable to uncondensable gas, loss and a negligible amount of coke.

I claim as my invention:

1. A cracking process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in an enlarged reactionzone, removing vapors and unvaporized oil from the reaction zone, flashdistilling the unvaporized oil in a reduced pressure zone by pressurereduction, simultaneously heating charging I oil for the process toconversion temperature under pressure while flowing in a restrictedstream through a heating zone and then discharging the same directlyinto the reduced pressure zone, removing vapors from the reducedpressure zone, iractionating the last-named vapors and the vaporsremoved from the reaction zone and separating' therefrom a relativelyheavy reflux and a lighter reflux, introducing the heavy reflux direct-1y to the reaction zone, heating the lighter reflux to cracldngtemperature in a second heating zone and thence discharging the sameinto the reaction zone, and finally condensing theiraction ated vapors.

2. A cracking process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in an enlarged reactionzone, removing vapors and unvaporized oil from the reaction zone, flashdistilling the unvaporized oil in a reduced pressure zone by pressurereduction, simultaneously passing charging oil for the process through aheating zone and heating the same therein to cracking temperature underpressure, thence discharging the heated charging oil directly into thereduced pressure zone, subjecting the vapors evolved in the reducedpressure zone and those removed from the reaction zone to commonfractionation and separating from the commingled vapors a relativelyheavy reflux and a lighter reflux, introducing the heavy reflux directlyto the reaction zone, heating the lighter reflux to higher crackingtemperature than the charging oil and thence discharging the same intothe reaction zone, and finally condensing the fractionated vapors.

3. The process as defined in claim 1 further characterized in that saidchar ing oil is of higher boiling point than said lighter reflux, thefirst-mentioned heating zone through which the charging oil is passedbeing maintained at lower temmrature than said second heating zone inwhich the lighter reflux is heated.

MARION W. BARNES.

